Inadequately controlled postoperative pain remains an important clinical problem that can delay mobilisation and increase postoperative complications. Intravenous patient-controlled analgesia (PCA) is a commonly used modality, but traditional fixed-rate basal infusion modes may not align with the biphasic and fluctuating nature of postoperative pain. A fixed background rate can lead to periods of insufficient analgesia or, conversely, unnecessary opioid exposure when pain intensity falls.
Network-integrated PCA pumps have introduced the capability for variable-rate feedback infusion, in which the background infusion rate is dynamically adjusted in response to real-time patient demand. This adaptive approach aims to better match analgesic delivery to patient needs and potentially reduce overall opioid exposure while maintaining adequate pain control.
This trial is a multicentre, randomised, double-blind, controlled study conducted at three hospitals in China. The trial will compare cumulative opioid consumption between variable-rate feedback infusion and fixed-rate basal infusion modes of intravenous PCA following mixed elective surgery under general anaesthesia.
The study will enrol 1,170 adult patients aged 18–65 years with American Society of Anaesthesiologists (ASA) physical status I–III. Eligible participants are those scheduled for elective mixed surgical procedures, including thoracic, abdominal, spinal, orthopaedic and cranial surgeries, performed either via minimally invasive or open approaches. Written informed consent will be obtained from all participants before enrolment.
Participants will be randomised in a 1:1 ratio to either the fixed-rate basal infusion group or the variable-rate feedback infusion group. The trial is described as double-blind; the source indicates both groups and assessments will be conducted in a manner designed to blind relevant parties, although specific blinding procedures beyond randomisation are not detailed in the source.
Both study arms will receive the same standardised PCA solution containing sufentanil. In the fixed-rate basal infusion group, the background infusion rate remains constant according to the protocol-defined setting.
In the variable-rate feedback infusion group, the PCA device will automatically adjust the background infusion rate based on patient demand. The predefined algorithm increases the background infusion by 0.5 mL/hour when patients deliver demand boluses during lockout intervals and decreases the background infusion by 0.5 mL/hour after 1 hour with no demand boluses. The source reports these stepwise adjustments but does not provide the absolute starting or maximum/minimum infusion rates; those details were not reported in the source.
Both groups will use an identical PCA solution of sufentanil prepared according to the study protocol. The source states the background adjustment rules for the variable-rate arm but does not provide detailed concentrations, bolus sizes, lockout durations, or maximum allowable infusion rates. Those specifics were not reported in the source material.
The primary outcome is the total cumulative opioid consumption at 48 hours postoperatively. This includes sufentanil delivered via PCA plus any opioid-equivalent rescue analgesics administered during the postoperative period.
Key secondary outcomes listed in the source include:
These secondary measures will help determine analgesic efficacy and rescue requirements in each group.
Exploratory outcomes specified in the protocol include:
The source indicates these outcomes will be assessed at predefined postoperative time points, but it does not list those exact time points in the provided summary.
The study has been approved by the Institutional Review Board of Beijing Tiantan Hospital (KY2025-387-02), the Affiliated Hospital of Youjiang Medical University for Nationalities (YYFY-LL-2026-006), and the Second Affiliated Hospital of Hainan Medical University (2026-K140-01). The investigators will conduct the trial in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. Written informed consent will be obtained from all participants prior to enrolment.
Findings from the trial will be disseminated through peer-reviewed journals and scientific conferences. A summary of the results will also be made available to participants on request. The trial is registered under the identifier NCT07361822.